Image pickup apparatus and display control method

ABSTRACT

An image pickup apparatus uses an image pickup device. A manual focus adjusting unit is configured to control a focus lens in response to a user&#39;s input operation. An edge detecting unit is configured to detect edge components from an image signal obtained by the image pickup device and to output detection levels of the detected edge components. A color signal replacement unit is configured to replace a signal of a pixel corresponding to the detection level with a predetermined color signal when the detection level satisfies a predetermined condition. A display unit is configured to display an image based on an output image signal from the color signal replacement unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/018,531, filed Feb. 1, 2011, which is a continuation of U.S.application Ser. No. 11/509,149, filed Aug. 24, 2006, which claimspriority from Japanese Patent Application No. JP 2005-243585, filed Aug.25, 2005, the disclosures of which are hereby incorporated by referenceherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image pickup apparatus for capturingan image by using a solid image pickup device and a method ofcontrolling the display of the same. More specifically, the presentinvention relates to an image pickup apparatus having a manual focusingfunction and a method of controlling the display of the same.

2. Description of the Related Art

Known image pickup apparatuses using a solid image pickup device, suchas a digital still camera and a digital video camera, generally have anauto focusing (AF) function of automatically bring an image into focus.However, in recent years, many image pickup apparatuses have a manualfocusing function of manually bring an image into focus. In such animage pickup apparatus, usually, a picked up image is displayed on amonitor (or an electronic viewfinder), such as an LCD (liquid crystaldisplay), provided at the rear surface thereof. A user confirms thefocus adjusted state by viewing the monitor.

In the image pickup apparatuses with an auto focusing function accordingto the related art, some images, as the result of the focus adjustment,are displayed on a monitor such that a user can recognize when focusinghas occurred. For example, some image pickup apparatuses have a functionof displaying a lock mark when focusing is completed or a function ofhighlighting an area brought into focus among divided areas of an image.Also, some image pickup apparatuses apply a color that is different fromthe color of the subject to the edge of a subject brought into focus(for example, JP-A-2001-8085 (paragraph [0019] and FIG. 4).

Meanwhile, some of the image pickup apparatuses with a manual focusingfunction according to the related art display edge detection informationon a monitor as a bar graph, and some highlight an area brought intofocus among divided areas on a monitor . Further, some image pickupapparatuses change the color of each of the divided areas according tothe focused state based on edge detection information (for example,JP-A-6-113183 (paragraphs to [0039] and FIG. 2).

However, in a technique for showing a focused state for every dividedarea at the time of adjusting focus by manual operation, when aplurality of subjects exist in the same area, a user cannotdifferentiate which subject is focused. For this reason, it is necessaryto change composition so as to reset an area or focus on a specificarea.

Further, in order for precise focus adjustment, it is preferable thatthe user view the sharpness of the subject displayed on the monitor anddiscriminate the adjusted state. However, most monitors provided on therear surfaces of image pickup apparatuses do not have such a resolutionand size that the user can precisely confirm the sharpness of a subjectdue to the size or the manufacturing cost. For this reason, it isdifficult to precisely adjust focus by manual operation by using avisual observation method.

Accordingly, it is desirable to provide an image pickup apparatuscapable of precisely adjusting manual focus while viewing an imagedisplayed on a monitor.

It is also desirable to provide a method of controlling the display ofan image pickup apparatus capable of precisely adjusting manual focuswhile viewing an image displayed on a monitor.

SUMMARY OF THE INVENTION

According to an embodiment of the present invention, there is providedan image pickup apparatus using an image pickup device. The image pickupapparatus includes a manual focus adjusting unit configured to control afocus lens in response to a user's input operation; an edge detectingunit configured to detect edge components from an image signal obtainedby image pickup and for outputting detection levels of the detected edgecomponents; a color signal replacement unit configured to replace asignal of a pixel corresponding to the detection level with apredetermined color signal when the detection level satisfies apredetermined condition; and a display unit configured to display animage based on an output image signal from the color signal replacementmeans.

In the image pickup apparatus, the color signal replacement unitreplaces, of image signals obtained by image pickup, the signal of apixel whose detection level of an edge component detected by the edgedetecting means satisfies the predetermined condition. Therefore, in apicked up image displayed on the display unit, an edge portion of asubject in which the degree of focusing is relatively high is displayedby a predetermined color.

For example, color signal replacement may be performed using differentcolor signals according to the detection levels of edge components. Inthis case, in the picked up image displayed on the display unit, theedge portion of the subject is displayed by different colors accordingto the focusing degree.

According to the image pickup apparatus of the invention, in a picked upimage displayed on the display unit, an edge portion of a subject onwhich a focusing degree is relatively high is displayed by apredetermined color. Therefore, a user manually taking focus can easilyconfirm the edge portion of the subject on which the focusing degree isrelatively high with his or her eyes and thus more precisely adjustfocus.

Further, when the color signal replacement is performed using differentcolor signals according to the detection levels of edge components, inthe picked up image displayed on the display unit, the edge portion ofthe subject is displayed by different colors according to the focusingdegree. Therefore, the user can easily confirm whether the subject isbrought into focus, and thus further more precisely adjust the focus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the main configuration of animage pickup apparatus according to an embodiment of the invention;

FIG. 2 is a timing chart of various signals of a display processingcircuit in an edge emphasis mode;

FIG. 3 is a view illustrating an example of an image displayed on amonitor in the edge emphasis mode;

FIG. 4 is a view illustrating the configuration of an edge detector anda color signal output unit according to the first embodiment;

FIG. 5 is a flow chart illustrating the process of the edge detectoraccording to the first embodiment;

FIG. 6 is a view illustrating the configuration of an edge detector anda color signal output unit according to a second embodiment;

FIG. 7 is a flow chart illustrating the processes of the edge detectorand the color signal output unit according to the second embodiment; and

FIG. 8 is a flowchart illustrating the control process of amicrocontroller in the edge emphasis mode.

DETAILED DESCRIPTION

Hereinafter, embodiments of the invention will be described in detailwith reference to the accompanying drawings.

FIG. 1 is a block diagram showing the main configuration of an imagepickup apparatus according to an embodiment of the invention.

The image pickup apparatus shown in FIG. 1 includes an optical block 1,an image pickup device 2, an analog front end (AFE) circuit 3, a cameraprocessing circuit 4, a display processing circuit 5, a monitor 6, amicrocontroller 7, and an input unit 8. Further, the image pickupapparatus includes a motor 12 for driving a focus lens 11 of the opticalblock 1, a motor control circuit 13 for controlling the motor 12, and atiming generator (TG) 14 for driving the image pickup device 2.

The optical block 1 includes: a lens for focusing light from a subjecton the image pickup device 2; a driving mechanism for moving the lens tofocus the lens or zoom in the subject; a shutter mechanism; and an irismechanism. In FIG. 1, specifically, the motor 12 is shown as the drivingmechanism for the focus lens 11. The motor 12 operates in response to adriving control signal from the motor control circuit 13 to move thefocus lens 11. The motor control circuit 13 controls the operation ofthe motor 12 in response to a control signal from the microcontroller 7.

The image pickup device 2 is a solid image pickup device, such as acharge-coupled device (CCD) or a complementary metal oxide semiconductor(CMOS). The image pickup device 2 is driven on the basis of a timingsignal output from the TG 14, and converts incident light from thesubject into an electric signal. The TG 14 outputs a timing signal underthe control of the microcontroller 7.

The AFE circuit 3 performs a sample-and-hold operation on an imagesignal output from the image pickup device 2 by a CDS (Correlated DoubleSampling) process to obtain a good S/N (Signal/Noise) ratio, controlsthe gain of the image signal by an AGC (Auto Gain Control) process,converts the image signal with the controlled gain into a digital imagesignal, and then outputs the digital image signal.

The camera processing circuit 4 performs various camera signalprocesses, such as AF (Auto Focus), AE (Auto Exposure), and whitevalance adjustment, or some of the various camera signal processes onthe image signal from the AFE circuit 3.

The display processing circuit 5 generates an image signal to bedisplayed on the monitor 6 from the image signal supplied from thecamera processing circuit 4, and supplies the generated image signal tothe monitor 6 so as to display an image. In order for such functions,the display processing circuit 5 includes, as one of functional blocks,a resolution changing unit 51 for changing the resolution of the inputimage signal in accordance with the resolution of the monitor 6.Further, in this embodiment, the display processing circuit 5 includesan edge detector 52, a color signal output unit 53, and a replacementprocessor 54, as function blocks for changing the display color of anedge portion according to an edge detection result at the time ofselecting a manual focusing mode. The edge detector 52, the color signaloutput unit 53, and the replacement processor 54 will be describedbelow.

The monitor 6 is, for example, an LCD, and displays, for example, acamera still image during photographing or an image reproduced on thebasis of data recorded in a recording medium (not shown). The monitor 6is provided at, for example, the rear surface of the image pickupapparatus. The monitor 6 may be provided as an electronic viewfinder.Alternatively, both a rear monitor and an electronic viewfinder may beseparately provided.

The microcontroller 7 includes, for example, a CPU (Central ProcessingUnit), a ROM (Read Only Memory), and a RAM (Random Access Memory). Themicrocontroller 7 executes programs stored in, for example, the ROM tototally control the individual units of the image pickup apparatus or toperform various operations for such control.

The input unit 8 includes operation keys used for a user's inputoperation, a dial, a lever, and outputs a control signal correspondingto the input operation to the microcontroller 7. The input unit 8 maybe, for example, a known shutter release button. In particular, in thisembodiment, the input unit 8 maybe a switch, such as a focus ring or afocus button, for bringing into focus by a manual operation, or a switchfor switching between an auto-focusing mode and a manual focusing modeand turning on/off a mode in which an edge is emphasized on the basis ofthe edge detection result (referred to as an edge emphasis mode).

In the image pickup apparatus, the image pickup device 2 receives light,converts the received light into an electric signal, and outputs theelectric signal to the AFE circuit 3. The AFC circuit 3 performs the CDSprocess or the AGC process on the electric signal and converts theprocessed signal into a digital image signal. The camera processingcircuit 4 performs an image-quality correcting process on the digitalimage signal supplied from the AFE circuit 3, converts the processedsignal into a brightness signal and a color difference signal, andoutputs the brightness signal and the color difference signal.

The image data output from the camera processing circuit 4 is suppliedto the display processing circuit 5. The display processing circuit 5converts the image data into a display image signal and displays acamera still image on the monitor 6 on the basis of the display imagesignal. Further, when the microcontroller 7 is instructed to record thecamera still image by, for example, a user's input operation through theinput unit 8, the image data from the camera processing circuit 4 issupplied to a CODEC (encoder-decoder) (not shown). The CODEC performs apredetermined compressing/encoding process on the image data and recordsthe processed data in a recording medium (not shown). The cameraprocessing circuit 4 supplies image data to the CODEC frame-by-framewhen still images are recorded. When moving images are recorded, thecamera processing circuit 4 continuously supplies the processed imagedata to the CODEC.

Next, the focusing operation of the image pickup apparatus will bedescribed.

The image pickup apparatus has an auto-focusing mode and a manualfocusing mode. In the auto-focusing mode, due to, for example, an AFdetecting function of the camera processing circuit 4, a focusevaluation value representing contrast can be obtained by integratinghigh-frequency components of a predetermined region of the image. Then,the microcontroller 7 controls the position of the focus lens 11 suchthat the focus evaluation value is maximized, whereby the focus lens 11automatically moves to a focused position.

Meanwhile, in the manual focusing mode, the focus lens 11 moves inresponse to the operation of the focus ring of the input unit 8. In themanual focusing mode, it is possible to select the edge emphasis mode onthe monitor 6 for changing the color of an edge portion and displayingthe edge with the changed color. When the edge emphasis mode isselected, the edge detector 52, the color signal output unit 53, and thereplacement processor 54 of the display processing circuit 5 start tooperate.

The edge detector 52 detects edge components of every pixel from theimage signal output from the resolution changing unit 51. Morespecifically, the edge detector 52 calculates detected levels of theedge components (edge levels) by, for example, performing high-pass(band-pass) filtering on the image signal output from the resolutionchanging unit 51 for every pixel. When the edge level detected by theedge detector 52 is equal to or higher than a predetermined value, thecolor signal output unit 53 sets an edge detection flag for thereplacement processor 54 to a high level and outputs a color signalcorresponding to the edge level. When the edge detection flag suppliedfrom the edge detector 52 is at the high level, the replacementprocessor 54 replaces the image signal from the resolution changing unit51 with the color signal from the color signal output unit 53. In thisway, the image signal for an edge having the edge level equal to orhigher than the predetermined value is replaced with the color signalcorresponding to the level and display according to the color signal isperformed on the monitor 6.

FIG. 2 is a timing chart of various signals in the display processingcircuit in the edge emphasis mode.

Specifically, FIG. 2 shows an edge level detected by the edge detector52, an edge flag, and a color signal output from the color signal outputunit 53 when edge detection is performed along a horizontal line L1 onan image 21 shown in the upper side of FIG. 2. The image 21 is based onan image signal input to the edge detector 52 and the replacementprocessor 54.

As shown in FIG. 2, the edge levels of pixels on the both sides of eachof edges E1 to E3 on the horizontal line L1 are equal to or higher thana predetermined value, and thus the edge detection flags for thecorresponding pixels are changed to the high level. According to theedge level, the level of the color signal of the color signal outputunit 53 varies. In this case, basically, the higher the edge level is,the higher brightness becomes. The replacement processor 54 replaces thesignal for the pixel in which the edge detection flag is at the highlevel, with the color signal for the corresponding pixel from the colorsignal output unit 53 and outputs the color signal.

FIG. 3 is a view showing an example of an image displayed on the monitorin the edge emphasis mode.

An image 22 shown in FIG. 3 is an image output from replacementprocessor 54 and is then displayed on the monitor 6 when the edgeemphasis mode is selected and the image 21 shown in FIG. 2 is input tothe replacement processor 54. As shown in FIG. 2, since the edge levelsat the edges E2 and E3 are high, the color of the pixels on the bothsides of each of edges E2 and E3 is converted into a color having highbrightness. Further, as compared to the edges E2 and E3, since the edgelevel at an edge E1 is lower, the color of the pixels at both sides ofthe edge E1 is converted into a color having lower brightness.

Typically, as the focus lens 11 approaches the focused position, thedetection value of the edge component becomes larger. For this reason,according to the above-mentioned image display method, when the edgelevel of an edge portion of a subject is equal to or higher than apredetermined value, the edge portion is displayed in a color notconcerned with the original image of the subject. As a result, a usercan easily view the edge portion. Further, as the degree of focusing onthe subject increases, the edge portion is displayed in, for example, abrighter color so as to be emphasized. Therefore, it is possible for auser to simply and surely confirm which subject is brought into focus byviewing the monitor 6.

Even in a situation in which, due to the limitations of the brightnessor resolution of the monitor 6, surrounding circumstances, and so on, itis difficult to view the resolution of the edge in a state in which apicked up image is normally displayed without any change, it is possibleto simply confirm which subject is brought into focus and the degree offocusing. Therefore, it is possible to improve the operationality of auser in the manual focusing mode without increasing the manufacturingcost or size of the monitor 6.

In the examples shown in FIGS. 2 and 3, only the signal for the pixelwhose edge level is equal to or higher than a predetermined value isreplaced with a color signal for the corresponding pixel. However, thepulse width of the edge detection flag may be set to a width thatcorresponds to a plurality of pixels centered on the pixel whose edgelevel is equal to or higher than the predetermined value, which makes itpossible to replace the signal for pixels in a certain range containingthe pixel whose edge level is equal to or higher than the predeterminedvalue with the color signal for the pixels in the certain range. Thetotal width of pixels subjected to the replacement may be set such thatthe edge portion on the monitor 6 is easily viewed to the user.

Next, a specific example of the configuration between the edge detector52 and the color signal output unit 53 will be described. FIG. 4 is aview showing the configuration of the edge detector and the color signaloutput unit according to the first embodiment.

An edge detector 52 a shown in FIG. 4 detects the edge level of eachpixel by performing a high-pass filtering on the image signal outputfrom the resolution changing unit 51. When the detected edge level isequal to or higher than a predetermined value, the edge detector 52 asets the edge detection flag to a high level. Further, the edge detector52 a calculates a variable n corresponding to the edge level and outputsthe calculated variable n to a color signal output unit 53 a. The colorsignal output unit 53 a includes a color table 531 in a ROM in which aplurality of color signals used by the replacement processor 54 forreplacement at edge portions is stored. The color signal output unit 53a reads, from the color table 531, one of the color signalscorresponding to the variable n designated by the edge detector 52 a,and outputs the read color signal to the replacement processor 54.

FIG. 5 is a flow chart illustrating the flow of the processes of theedge detector according to the first embodiment.

[Step S101] The edge detector 52 a detects an edge level eLV from aninput image signal.

[Step S102] The edge detector 52 a determines whether the detected edgelevel eLV is lower than a minimum threshold value eTHmin or not.

[Step S103] When it is determined in Step S102 that the edge level eLVis lower than the minimum threshold value eTHmin, the edge detector 52 asets the edged detection flag for the replacement processor 54 to a lowlevel and then finishes the process in respect to the correspondingpixel. Therefore, the replacement processor 54 outputs the signal forthe pixel to be processed, without replacement.

[Step S104] When it is determined in Step S102 that the edge level eLVis equal to or higher than the minimum threshold value eTHmin, the edgedetector 52 a sets the edge level flag to a high level.

[Step S105] The edge detector 52 a sets the variable n to ‘1’.

[Step S106] The edge detector 52 a sets an n-th threshold value eTHn asa threshold value eTH.

[Step S107] The edge detector 52 a determines whether the detected edgelevel eLV is lower than the threshold value eTH or not.

[Step S108] When it is determined in Step S107 that the edge level eLVis equal to or higher than the threshold value eTH, the edge detector 52a increases the variable n by ‘1’. Then, the edge detector 52 a performsthe process of Step 5106.

[Step S109] When it is determined in Step S107 that the edge level eLVis lower than the threshold value eTH, the edge detector 52 a designatesan address n for the color table 531 (ROM) and selects the color signalstored in the address n. Then, the edge detector 52 a reads the colorsignal from the designated address n of the color table 531 and outputsthe read color signal to the replacement processor 54. The replacementprocessor 54 replaces the signal for the pixel to be processed with thecolor signal read from the color table 531.

In the above-mentioned process, only when the detected edge level eLV isequal to or higher than the threshold value eTH, the pixel to beprocessed is determined as an edge, and the replacement processor 54performs the signal replacement. Further, the edge detector 52 a reads adifferent color signal corresponding to the edge level eLV from thecolor table 531 and outputs the read color signal to the replacementprocessor 54. The color signals stored in the color table 531 are notconcerned with the signal of the picked up image, and different colorsare assigned according to the variable n. It is preferable that the edgeportion is displayed in a striking color as the variable n increasessuch that the user can easily notice the edge level (that is, a focusingstate) of the edge portion on the monitor 6. Besides, for example, acolor signal having a higher brightness as the variable n increases isrecorded in the color table 531, whereby the edge portion can bedisplayed in a brighter color emphatically as the edge level becomeshigher.

In the first embodiment, the color signal output unit 53 a may beconfigured to have only a function of reading the color signal from thedesignated address; however, a memory region corresponding to thevariable n needs to be prepared as the color table 531.

FIG. 6 is a view showing the configuration of an edge detector and acolor signal output unit according to a second embodiment.

An edge detector 52 b shown in FIG. 6 detects the edge level of eachpixel by performing high-pass filtering on the image signal output fromthe resolution changing unit 51. When the detected edge level is equalto or higher than a predetermined value, the edge detector 52 bdetermines the pixel to be processes as an edge and sets the edgedetection flag to a high level. Further, when the edge detector 52 bdetermines the pixel to be processed as an edge, it outputs a variableDF corresponding to the edge level to a color signal output unit 53 b.

The color signal output unit 53 b stores a reference color signal CLR asa reference of color signals used in the replacement processor 54 in acolor storage unit 532 composed of a ROM in advance, amplifies thereference color signal CLR so as to have a gain corresponding to thevariable DF from the edge detector 52 b by the gain adjusting unit 533,and outputs the amplified color signal to the replacement processor 54.Here, a reference red color signal CLR(R) is stored in the color storageunit 532 as an example.

FIG. 7 is a flow chart illustrating the flow of the processes of theedge detector and the color signal output unit according to the secondembodiment.

[Step S201] The edge detector 52 b detects the edge level eLV from aninput image signal.

[Step S202] The edge detector 52 b sets the threshold value eTH to becompared with the edge level eLV.

[Step S203] The edge detector 52 b calculates a differential value(variable DF) by subtracting the threshold value eTH from the edge leveleLV.

[Step S204] The edge detector 52 b determines whether the variable DF issmaller than ‘0’ or not.

[Step S205] When it is determined in Step 5204 that the variable DF issmaller than ‘0’, the edge detector 52 b sets the edged detection flagfor the replacement processor 54 to a low level and then finishes theprocess in respect to the corresponding pixel. Therefore, thereplacement processor 54 outputs the signal for the pixel to beprocessed, without replacement.

[Step S206] When it is determined in Step 5204 that the variable DF isequal to or larger than ‘0’, the edge detector 52 b determines the pixelto be processed as an edge, sets the edge level flag to a high level,and outputs the variable DF to the gain adjusting unit 533 of the colorsignal output unit 53 b.

[Step S207] The gain adjusting unit 533 reads the reference red colorsignal CLR(R) from the color storage unit 532, multiplies the value bythe variable DF to adjust the gain of the reference red color signalCLR(R), and outputs the adjusted color signal to the replacementprocessor 54. In this way, the replacement processor 54 replaces thesignal for a target pixel with the color signal from the gain adjustingunit 533.

In the above-mentioned process, only when the variable DF is equal to orlarger than ‘0’, the edge detector 52 b determines the pixel to beprocessed as an edge, and thus the replacement processor 54 performs thesignal replacement. Further, the color signal output unit 53 b modulatesa single color signal by the gain corresponding to the edge level eLV,and thus the replacement processor 54 performs a process such that, asthe edge level eLV becomes higher, the edge portion is displayed in amore vivid (brighter) color.

In the second embodiment, as compared to the first embodiment, the edgedetector 52 b has a simpler structure, and the memory capacity of thecolor storage unit 532 decreases; however, an operational circuit isrequired as the gain adjusting unit 533.

Next, control in the edge emphasis mode will be described in detail.FIG. 8 is a flow chart illustrating the flow of the control process ofthe microcontroller in the edge emphasis mode. It is assumed that at theprocess start time of FIG. 8, the manual focusing mode and the edgeemphasis mode are in an ON state.

[Step S301] The microcontroller 7 determines whether the shutter releasebutton of the input unit 8 is in a halfway pressed state or not. If theshutter release button is in the halfway pressed state, the processproceeds to Step S308. However, if not, the process proceeds to StepS302. Further, when the shutter release button is pressed halfway, animage pickup operation control process and various image correctingprocesses substantially the same as that in which the picked up-imagesignal is recorded on the recording medium are performed. For example,AE control is performed again by the camera processing circuit 4 and themicrocontroller 7. As a result, an image is displayed on the monitor 6with the quality the same as or similar to while recording.

[Step S302] The microcontroller 7 determines whether the focus ring (ora focus button) of the input unit 8 has been operated and thus it isrequired to operate the focus lens 11. If it is required to operate thefocus lens 11, the process proceeds to Step S303. However, if not, theprocess proceeds to Step S304.

[Step S303] The microcontroller 7 turns on the edge emphasis displayfunction of the display processing circuit 5 (that is, turns on the edgedetector 52, the color signal output unit 53, and the replacementprocessor 54). Further, the microcontroller 7 resets the count value ofan internal counter to ‘0’. Then, the process proceeds to Step 5307.

[Step S304] The microcontroller 7 determines whether the edge emphasisfunction of the display processing circuit 5 is in the ON state or not.If the edge emphasis function is in the ON state, the process proceedsto Step S305. However, if not, the process proceeds to Step S308.

[Step S305] The microcontroller 7 increases the count value of theinternal counter by ‘1’. The increase of the count value is performedafter a constant time from the previous increase of the count value orreset of the count value. In this example, the count operation isperformed whenever one frame (of the display image) is output.

[Step S306] The microcontroller 7 determines whether the count value isequal to or larger than N (N≧1) or not, that is, whether the focus lens11 has been stationary until counting to N. If the count value is N, theprocess proceeds to Step S308. However, if not, the process proceeds toStep S307.

[Step S307] The microcontroller 7 operates the display processingcircuit 5 to perform the edge emphasis display function. That is, underthe control of the microcontroller 7, the edge detector 52 detectsedges, the color signal output unit 53 outputs color signalscorresponding to the edge levels, and the replacement processor 54replaces the signal for each pixel in the edge portion with the colorsignal for the corresponding pixel. Then, the process returns to StepS301.

[Step S308] The microcontroller 7 turns off the edge emphasis displayfunction of the display processing circuit 5 (that is, turns off theedge detector 52, the color signal output unit 53, and the replacementprocessor 54).

In the above-mentioned control example, even when the edge emphasis modeis turned on, the edge emphasis display function of the displayprocessing circuit 5 does not necessarily need to be performed, and theoperation is controlled according to the operational state of the focuslens 11. First, basically, when the manual focus operation is performed(Step S302), the edge emphasis display function starts (Step S303).During a period for which the focusing operation is continuouslyperformed, the edge emphasis display function is in the ON state suchthat display for emphasizing the edges is continuously performed.

However, after the focusing operation, that is, after stopping the focuslens 11, if the focus lens 11 is not required to move for a constanttime until the count value becomes N (Step S306), it is considered thatthe user intends to complete the focusing and confirm the focused stateof the picked up image. Therefore, the edge emphasis display function isturned off (Step S308). Thus, it is possible to improve theoperationality of a user and to reduce power consumption for anoperation not performed in the displaying processing circuit 5.

Further, when the shutter release button is in the halfway pressed state(Step S301), in the manual focusing mode, it is considered that thefocusing has been completed and the recording operation has started.Therefore, the edge emphasis display function is turned off (Step S308).Thus, it is possible to improve a recording response to the operation ofthe shutter.

In each of the above-mentioned embodiments, the edge components aredetected from the image signal by the display processing circuit 5, butit may be detected by, for example, the camera processing circuit 4. Ifthe image pickup apparatus has an auto-focus mode, the edge detection(high-frequency component detection) function for auto-focusing by thecamera processing circuit 4 may be used for the edge emphasis displayfunction in the manual focusing mode.

However, in a related art image pickup apparatus, typically, the numberof pixels of the image pickup device 2 or the number of pixels of animage capable of being recorded on a recording medium is larger than thenumber of pixels of the monitor 6. For this reason, an image signalsubjected to the edge detection of the camera processing circuit 4 haspixels larger than those of an image signal subjected to the edgedetection of the display processing circuit 5. Therefore, frequencyranges that pass the image signals subjected to the edge detection ofthe camera processing circuit 4 and the display processing circuit 5 inthe edge detection process are different from each other, which causesthe configurations of filters and filter coefficients used to bedifferent from each other.

Therefore, in order to use the edge detection result of the cameraprocessing circuit 4 to control the edge detection or color signaloutput in the display processing circuit 5, a process of converting theedge detection result according to the number of pixels is required,resulting in an increase in the circuit size or the manufacturing cost.Meanwhile, when the display processing circuit 5 detects the edges fromthe image signal in which the number of pixels (resolution) has beendown-converted, it is possible to simplify the configuration of an edgedetection circuit and to further reduce the circuit size or themanufacturing cost. However, when the edge detection result of thecamera processing circuit 4 is used, it is possible to improve theaccuracy of edge detection or emphasis display. For example, it ispossible to display the edge portion with high definition (clearly) in aregion where the spatial frequency is high on the picked up image.

Further, in each of the above-mentioned embodiments, the color to whichthe color of the edge portion is changed to varies according to the edgedetection level. However, it may be possible that, as the edge detectionlevel becomes higher, the color of a wider region in the vicinity of theedge is changed to a single color. In this case, as the edge detectionlevel becomes higher, the pulse width of the edge detection flag iscontrolled to become wider such that the signals for a plurality ofpixels adjacent to the pixel, as well as the signal for the objectpixel, are replaced with the same color signal. In this way, as thedegree of focusing gets higher, the edge portion is displayed by athicker line. Therefore, the user can easily confirm the subject broughtinto focus on the monitor 6.

The invention can be generally applied to various image pickupapparatuses using a solid image pickup device and other apparatuses,such as a cellular phone and a PDA (Personal Digital Assistants), havingsuch an image pickup function and a manual focusing mode.

In each of the above-mentioned embodiments, the edge detector 52, thecolor signal output unit 53, and the replacement processor 54 arecomposed of dedicated hardware circuits. However, some of the processingfunctions or some of the edge detector 52, the color signal output unit53, and the replacement processor 54 (for example, the function of theedge detector 52) maybe performed by software in the microcontroller 7.Further, a program for performing the software may be installed in animage pickup apparatus from a portable storage medium, such as a flashmemory, or through a network.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

The invention claimed is:
 1. An image pickup apparatus, comprising: anedge detecting unit configured to detect edge components from an imagesignal obtained by an image pickup unit in response to detecting that afocus lens has been controlled by a user input operation, and to outputdetection levels of the detected edge components; a color signalgenerating unit configured to generate, in response to the detectionlevel satisfying a predetermined condition, a signal of a pixelcorresponding to the detection level with a predetermined color signal;and a display control unit configured to control display of, on adisplay, an image based on an output image signal received from thecolor signal generating unit.
 2. An image pickup apparatus according toclaim 1, further comprising: a manual focus adjusting unit configured tocontrol a focus lens of the image pickup device in response to the userinput operation.
 3. The image pickup apparatus according to claim 2,further comprising: a replacement operation control unit configured toturn on a color signal generating operation of the color signalgenerating unit in response to the focus lens of the image pickup devicestarting to be moved by the manual focus adjusting unit.
 4. The imagepickup apparatus according to claim 3, wherein in response to apredetermined period elapsing after the focus lens stops moving afterbeing moved by the manual focus adjusting unit, the replacementoperation control unit turns off the color signal replacement operationof the color signal generating unit.
 5. The image pickup apparatusaccording to claim 1, wherein in response to the detection levelsatisfying the predetermined condition, the color signal generating unitgenerates the signal for the corresponding pixel with a different colorsignal corresponding to the detection level.
 6. The image pickupapparatus according to claim 5, wherein in response to the detectionlevel satisfying the predetermined condition, the color signalgenerating unit changes the level of a predetermined color signalaccording to the detected level and generates the signal for thecorresponding pixel using the predetermined color signal with thechanged level.
 7. The image pickup apparatus according to claim 5,wherein the color signal generating unit generates the signal for thecorresponding pixel such that a brighter color is displayed as thedetection level becomes higher.
 8. The image pickup apparatus accordingto claim 5, wherein in response to the detection level satisfying thepredetermined condition, the color signal generating unit selects acolor signal corresponding to the detection level from a plurality ofdifferent color signals stored in advance, and performs replacementusing the selected color signal.
 9. The image pickup apparatus accordingto claim 1, wherein in response to the detection level satisfying thepredetermined condition, the color signal generating unit generates areplacement range of the color signal of the image signal according tothe detection level.
 10. The image pickup apparatus according to claim1, further comprising: a resolution changing unit configured to change,to the resolution of the display, the resolution of the image signalobtained by the image pickup unit, wherein the edge detecting unitdetects the edge components from a further output image signal receivedfrom the resolution changing unit.
 11. An image pickup method,comprising: detecting edge components from an image signal obtained byan image pickup unit in response to detecting that a focus lens has beencontrolled by a user input operation, and outputting detection levels ofthe detected edge components; generating, by use of a color signalgenerating unit and in response to the detection level satisfying apredetermined condition, a signal of a pixel corresponding to thedetection level with a predetermined color signal; and controllingdisplay of, on a display unit, an image based on an output image signalreceived from the color signal generating unit.
 12. The image pickupmethod according to claim 11, further comprising: controlling the focuslens of the image pickup device in response to the user input operation.13. The image pickup method according to claim 12, further comprising:turning on a color signal generating operation of the color signalgenerating unit in response to the focus lens of the image pickup devicestarting to be moved.
 14. The image pickup method according to claim 13,wherein in response to a predetermined period elapsing after the focuslens stops moving after being moved, the color signal replacementoperation is turned off.
 15. The image pickup method according to claim11, wherein in response to the detection level satisfying thepredetermined condition, the signal for the corresponding pixel with adifferent color signal corresponding to the detection level isgenerated.
 16. The image pickup method according to claim 15, wherein inresponse to the detection level satisfying the predetermined condition,the level of a predetermined color signal is changed according to thedetected level and the signal for the corresponding pixel using thepredetermined color signal with the changed level is generated.
 17. Theimage pickup method according to claim 15, wherein the signal for thecorresponding pixel is generated such that a brighter color is displayedas the detection level becomes higher.
 18. The image pickup methodaccording to claim 15, wherein in response to the detection levelsatisfying the predetermined condition, a color signal is selected whichcorresponds to the detection level from a plurality of different colorsignals stored in advance, and replacement using the selected colorsignal is performed.
 19. The image pickup method according to claim 11,wherein in response to the detection level satisfying the predeterminedcondition, a replacement range of the color signal of the image signalaccording to the detection level is generated.
 20. The image pickupmethod according to claim 11, further comprising: changing, to aresolution of the display unit, a resolution of the image signalobtained by the image pickup unit, wherein the detecting detects theedge components from a changed resolution image signal.
 21. Anon-transitory computer readable medium having stored thereon a programto cause an image pickup apparatus to perform an image pickup method,said method comprising: detecting edge components from an image signalobtained by an image pickup unit in response to detecting that a focuslens has been controlled by a user input operation, and outputtingdetection levels of the detected edge components; generating, by use ofa color signal generating unit and in response to the detection levelsatisfying a predetermined condition, a signal of a pixel correspondingto the detection level with a predetermined color signal; andcontrolling display of, on a display unit, an image based on an outputimage signal received from the color signal generating unit.
 22. Thecomputer readable medium according to claim 21, further comprising:controlling the focus lens of the image pickup device in response to theuser input operation.
 23. The computer readable medium according toclaim 22, further comprising: turning on a color signal generatingoperation of the color signal generating unit in response to the focuslens of the image pickup device starting to be moved.
 24. The computerreadable medium according to claim 23, wherein in response to apredetermined period elapsing after the focus lens stops moving afterbeing moved, the color signal replacement operation is turned off. 25.The computer readable medium according to claim 21, wherein in responseto the detection level satisfying the predetermined condition, thesignal for the corresponding pixel with a different color signalcorresponding to the detection level is generated.
 26. The computerreadable medium according to claim 25, wherein in response to thedetection level satisfying the predetermined condition, the level of apredetermined color signal is changed according to the detected leveland the signal for the corresponding pixel using the predetermined colorsignal with the changed level is generated.
 27. The computer readablemedium according to claim 25, wherein the signal for the correspondingpixel is generated such that a brighter color is displayed as thedetection level becomes higher.
 28. The computer readable mediumaccording to claim 25, wherein in response to the detection levelsatisfying the predetermined condition, a color signal is selected whichcorresponds to the detection level from a plurality of different colorsignals stored in advance, and replacement using the selected colorsignal is performed.
 29. The computer readable medium according to claim21, wherein in response to the detection level satisfying thepredetermined condition, a replacement range of the color signal of theimage signal according to the detection level is generated.
 30. Thecomputer readable medium according to claim 21, further comprising:changing, to a resolution of the display unit, a resolution of the imagesignal obtained by the image pickup unit, wherein the detecting detectsthe edge components from a changed resolution image signal.